Recently, a demand for outputting an image from the image information recorded in a magnetic recording medium is raised not only in the field of printing but in the general public accompanied with spread of a digital camera. Various methods such as a thermal transfer method, an ink-jet method and an electronic photographic method are practically used for responding such the demand. In this field, a method in which an image is obtained by scanning a silver halide photographic light-sensitive material with a laser light beam generated from a semiconductor laser or a laser diode (LED) is widely used because of the plentiful gradation of the silver halide photographic light-sensitive material. Such the method is more widely used since the scanning exposure by visible light is realized as a result of recent progress of a semiconductor laser or a wavelength converting element using a non-linear optical material.
However, the exposure time is extremely shorter and the light intensity is higher in the scanning exposure than those in the printing method through a negative film used in an ordinary mini-lab.
Accordingly, it is required that a natural image can be obtained by the scanning exposure with a laser light beam.
Moreover, in such the image forming method, it is also required that the dependency of characteristics of the photographic paper on the environmental condition is made smaller, such the property is also required to usual photographic paper. A technology for raising the stability of image is disclosed in Japanese Patent Publication Open to Public Inspection (JP O.P.I.) No. 5-19423 in which the stability of image can be obtained by overlapping a scanning line with the neighboring scanning line in a specific ratio. An image forming method is disclosed in JP O.P.I. No. 323521 in which a silver halide photographic light-sensitive material which reflects light in a ratio of not more than 30% of incident light, is exposed by scanning with light generated from a light source capable of being changed the light intensity to multi-steps for a exposing time of not more than 10.sup.-7 seconds per pixel.
The publication describes that a simple rapid processing is realized and the different of density and color between the pictorial image and the character or fine line can be reduced in such the technique. Moreover, JP O.P.I. No. 6-214351 discloses a method in which a rapid processing can be applied and a high quality image with a small unevenness density can be obtained by use of a laser light beam which is generated under a condition controlled at a temperature and the wavelength of light of the laser beam and the spectral sensitivity distribution has a specific relation, and the width of peak of spectral sensitivity is within a specific range.
However, these technologies are insufficient to obtain a naturally modulated image with high sharpness and contrast, since the stability of a high density image and that a low density image are different from each other with respect to a variation of temperature at the exposing, as a result of that a unnatural image is formed.
As the means for attaining the purpose of stably obtaining an image and that of raising the gradation of image for making a natural image, the use of a light-sensitive material in which a mixture of silver halide emulsions each having substantially the same spectral sensitivity and forming substantially the same chroma and different from each other in the sensitivity thereof are used, or a light-sensitive material which has a plural silver halide emulsion layers each having substantially the same spectral sensitivity and forming substantially the same chroma and different from each other in the sensitivity thereof are used, has be known. For example, JP O.P.I. 61-116350 discloses a method to obtain a suitable silver halide photographic light-sensitive material by using a mixture of at least two kinds of emulsion which have each a substantially the same average grain diameter and contain different amount of sensitizing dye and have relative sensitivity different 25% or more from each other.
Japanese Patent Publication No. 63-38693 discloses a method by which the gradation within the range of from 0.8 to 3.0 is raised by the use of a silver halide photographic light-sensitive material for laser light beam exposure which contains silver halide emulsions each having a specific grain diameter different from each other, in a specific ratio, and is hardened in a specific degree.
These methods are still insufficient to obtain a sharp and naturally modulated image with high contrast. JP O.P.I. No. 9-171237 discloses a technology of a photographic element having a property suitable for exposing for less than 50 microsecond. According to the technology, the photographic element has a specific range of .gamma. value, and the sharpness is improved when the exposure is made by scanning with laser light beam.
However, the gradation is not suitable and a natural image cannot be obtained when the photographic element using such the technology is used as a photographic element for printing an image through negative film according to usual method even though the sharpness can be improved when the photographic element is exposed to scanning by laser light beam. Accordingly, it is found that the image formation by the scanning exposure by laser light beam is not compatible with the image formation by exposure through a negative film.
On the other hand, JP O.P.I. Nos. 3-192346 and 4-276730 disclose a technology for improving the reciprocity low failure of silver halide photographic light-sensitive material by a fundamental technology in which a mixture of two or more kinds of emulsion which are different 40% or more from each other in the content of iridium. Moreover, JP O.P.I. No. 4-276739 discloses a black-and-white light-sensitive material improved in the pressure defect in which contains two or more kinds of emulsion different in the grain diameter from each other and the larger grains contain a larger amount of iridium.
However, these technologies are insufficient to obtain a high quality image by scanning exposure by a laser light beam, in concrete, the compatibility of sensitivity and the stability of property with respect to using environment namely the variation of sensitivity depending on the variation of time between the exposure and the processing. As a result of that a high quality image cannot be stably obtained.